This invention relates to glycidyl diamines, epoxy resins containing the glycidyl diamines, cured epoxy resins, and composites formed from the epoxy resins. In particular, it relates to compounds having two aromatic rings and a trifluoromethyl group and up to two amino glycidyl groups on each aromatic ring.
Epoxy resins are widely used as adhesives and in making composite materials. Epoxies based on aromatic amines have been made in order to obtain enhanced properties. See, for example, U.S. Pat. No. 4,451,645. The composite matrix most widely used in high performance fiber prepreg composites is composed of N,N,N',N'-tetraglycidyl(4,4'-methanobis[benzenamine]) and a 4,4'-diaminodiphenyl sulfone (DDS) hardener.
One of the major problems with this material, and with epoxy resins in general, is the formation of microcracks and the subsequent loss of mechanical properties in the harsh environments encountered in aerospace industrial applications. This micromechanical damage is believed to be due to the absorption of water, which is reported to act as plasticizer for epoxies. Due to plastization by the molar dilution by water, epoxy glass transition temperatures (T.sub.g) typically drop 10.degree. to 20.degree. C. for every 1 wt% water absorbed.